Electric circuit interrupter



March 14, 1939. w, D CROCKER 2,150,206

ELECTRIC CIRCUIT INTERRUPTER Filed Feb. 6, 193'? INVENTOR. 4. .27., flrvafew ATTORNEY.

Patented Mar. 14, 1939 UNITED STATES PATENT OFFICE William D. Crocker, Springfield, Mass, assignor to American Bosch Corporation, Springfield,

Mass., a corporation of New York Application February 6, 1937, Serial No. 124,445

6 Claims.

This invention relates to an interrupter for electrical circuits and particularly to an interrupter adapted to operate at high speeds, for example as an ignition interrupter for a high-speed multicylinder internal combustion engine.

In prior art interrupters of this type, it is common to open and close an electrical circuit by means of a movable contact point adapted to engage a stationary contact point. Usually the movable contact point is carried by a cam-actuated lever and the other point is carried by a normally stationary post. In such cases, where the lever is actuated at high speeds, as in multicylinder high-speed engines, the contact points engage with such force that the interrupter lever chatters or bounces upon the stationary contact causing an electrical spark to form and an arc to be drawn, which burns or oxidizes one or both contact points. Furthermore, this forceful engagement may cause a chipping of the points. Also this chattering shortens the period of closure of the circuit, or the saturation of the primary winding of the battery ignition coil or of the generating winding of a magneto, thereby decreasing the voltage and energy of the resulting ignition sparks at the sparkplugs and ultimately causing missing thereof. Also the spring pressure behind the lever may have to be so high for the high operating speed that the striking block of 30 the lever is excessively worn by the cam. These difliculties may arise notwithstanding that the speed of the interrupter is limited by the movement of a deflecting contact away from a stationary contact.

In accordance with the present invention the speed with which the contact points are separated is greatly increased while at the same time bouncing or chattering is minimized by making both contacts movable in opposite directions simul- 40 taneously. The extent of the movement of each of the contact points is thereby reduced to substantially half of that necessary for a single movable contact. Furthermore, since the travel of each lever is less than the travel required of a single lever, the momentum given to these parts is greatly reduced and the above noted difliculties inherent in giving a single deflecting member an extremely high velocity are thereby minimized.

The above and other objects and features of the invention Will in part be further set forth and in part be obvious to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawing, in which:

Fig. l is a plan view of an interrupter plate carrying interrupter levers mounted inv accordance with the present invention; Fig. 2 is a view similar to Fig. 1 with parts removed to more clearly show an adjusting plate for the interrupter levers; and Fig. 3 is a detail showing the interrupter lever stud and the manner of mount ing the interrupter levers thereon.

In the drawing, reference numeral i indicates a portion of an interrupter plate surrounding a multi-lobe cam 2. Interrupter levers 3 and 4 are pivoted scissor-wise upon a stud 5 which is mounted upon a plate 6 adjustable upon the interrupter plate by means of a slot '1 and an eccentric headed screw 8. The adjusting plate 8 is also provided with a pair of cars 9 having suitable slots for the holding screws 28 and H. In order to maintain the adjusting plate against lateral displacement relatively to the interrupter plate I, a plurality of raised lugs 52 are provided on the interrupter plate forming guides which permit the radial adjustment of the plate (5 while preventing lateral displacement thereof. By such radial adjustment of the plate 6 the contact opening, that is the distance by which the contacts 13 and M are separated upon actuation of the levers 3 and 4 by the cam 2, may be altered at will.

The interrupter levers 3 and d are preferably made of insulating material and carry the contact points l3 and M at their ends opposite the striking block portions which engage the lobes of the cam 2. The contact points l3 and M are electrically connected by springs l5 and it to binding posts I? and I8, the former of which binding posts is suitably insulated from the interrupter plate and the other of which is grounded thereon. One or both of the binding posts I! and i8 may be adjustable to vary the stress of springs l5 and 16 so as to maintain the interrupter levers 3 and 4 in proper relative position and balance. In the instance shown, the post I8 is formed of an angle iron, the base portion of which is provided with a slot l9 and a holding screw 20 by means of which the post I8 may be adjusted toward and away from the interrupter lever. Lugs 2| on the interrupter plate I prevent displacement of the binding post l8 in undesired directions.

In operation, at each period of ignition two of the lobes of the cam 2 simultaneously actuate the striker blocks of the levers 3 and A to quickly separate the contact points [3 and It to break the electrical circuit. This simultaneous and opposite movement is desirable in many electrical systems, and is particularly desirable in the ignition system of a high-speed internal combustion engine where the circuit is preferably interrupted with great rapidity. The dual lever system provides for an interruption substantially twice as fast as would be obtained if but a single lever were used in conjunction with a fixed contact point. Furthermore, it is not necessary to oscillate the levers through as large an arc as would be the case if but a single lever were used. The momentum given to each lever during the rapid actuation thereof by the cam lobe'is released and the wear upon the striking block is minimized. Bouncing of the levers upon making contact is therefore also minimized.

It is obvious that many modifications may be made without departing from the spirit of the invention as defined in the appended claims. For instance it is not necessary that either or both of the contact points be mounted on levers so long as both of them are movable, and that the interrupter may be used for temporarily closing electric circuits as well as opening them. Furthermore, other means, such as electromagnets, may be used instead of the cam for moving the contacts.

Having thus described my invention, what I claim is:

1, An interrupter forelectrical circuits comprising two oscillating levers, cooperative con tacts carried by said levers, a stud forming a common pivot for said levers, and a cam engaging said levers near the ends thereof remote from said contact points for positively oscillating the levers simultaneously in opposite directions about said stud to separate said contact points.

2. An interrupter for electrical circuits comprising two oscillating levers, cooperative contacts carried by said levers, a member forming a common pivot upon which said levers are mounted, a cam contacting the ends of said levers remote from said contact points for simultaneously oscillating the same in opposite directions about said common pivot, and means for moving said pivot toward and away from said cam to adjust the contact point opening.

3. An interrupter for an electrical circuit comprising two oscillating levers, cooperative contacts mounted upon said levers, said levers being mounted for oscillation around a common axis, a cam for actuating said levers in opposite directions about said axis, an interrupter plate surrounding said cam, a plate carrying the member forming said axis and being adjustable radially of said interrupter plate.

4. An interrupter for an electric circuit comprising two oscillating levers, cooperative contacts mounted on the ends of said levers, said levers being pivoted upon a common post, a cam adjacent the opposite ends of said levers for simultaneously actuating said levers in opposite directions around said post to separate said contacts, opposed springs for the levers to return the contacts into engagement, and means for adjusting the tension of one of said springs relative to the other.

5. An interrupter for an electrical circuit comprising two levers pivoted scissor-wise upon a common stud, cooperative contacts mounted upon said levers at one side of said stud, and a cam operative upon the opposite ends of said levers for actuating the same simultaneously in opposite directions about said stud to quickly separate said contacts.

6. An interrupter for an electrical circuit comprising two. levers pivoted scissor-wise upon a common stud, cooperative contacts mounted upon said levers at one side of said stud, a cam operative upon the opposite ends of said levers for actuating the same simultaneously in opposite directions about said stud to quickly separate said contacts, and means for bodily moving said levers toward and away from said cam for adjusting the distance by which said contacts are separated upon actuation of the levers by said cam.

WILLIAM D. CROCKER. 

